Custom price feed for ERC4626 (wUSDM and sFRAX)

contracts/IERC20.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC20/IERC20.sol)
+
+pragma solidity ^0.8.15;
+
+/**
+ * @dev Interface of the ERC-20 standard as defined in the ERC.
+ */
+interface IERC20 {
+    /**
+     * @dev Emitted when `value` tokens are moved from one account (`from`) to
+     * another (`to`).
+     *
+     * Note that `value` may be zero.
+     */
+    event Transfer(address indexed from, address indexed to, uint256 value);
+
+    /**
+     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
+     * a call to {approve}. `value` is the new allowance.
+     */
+    event Approval(address indexed owner, address indexed spender, uint256 value);
+
+    /**
+     * @dev Returns the value of tokens in existence.
+     */
+    function totalSupply() external view returns (uint256);
+
+    /**
+     * @dev Returns the value of tokens owned by `account`.
+     */
+    function balanceOf(address account) external view returns (uint256);
+
+    /**
+     * @dev Moves a `value` amount of tokens from the caller's account to `to`.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * Emits a {Transfer} event.
+     */
+    function transfer(address to, uint256 value) external returns (bool);
+
+    /**
+     * @dev Returns the remaining number of tokens that `spender` will be
+     * allowed to spend on behalf of `owner` through {transferFrom}. This is
+     * zero by default.
+     *
+     * This value changes when {approve} or {transferFrom} are called.
+     */
+    function allowance(address owner, address spender) external view returns (uint256);
+
+    /**
+     * @dev Sets a `value` amount of tokens as the allowance of `spender` over the
+     * caller's tokens.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * IMPORTANT: Beware that changing an allowance with this method brings the risk
+     * that someone may use both the old and the new allowance by unfortunate
+     * transaction ordering. One possible solution to mitigate this race
+     * condition is to first reduce the spender's allowance to 0 and set the
+     * desired value afterwards:
+     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
+     *
+     * Emits an {Approval} event.
+     */
+    function approve(address spender, uint256 value) external returns (bool);
+
+    /**
+     * @dev Moves a `value` amount of tokens from `from` to `to` using the
+     * allowance mechanism. `value` is then deducted from the caller's
+     * allowance.
+     *
+     * Returns a boolean value indicating whether the operation succeeded.
+     *
+     * Emits a {Transfer} event.
+     */
+    function transferFrom(address from, address to, uint256 value) external returns (bool);
+}

contracts/IERC20Metadata.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.1.0) (token/ERC20/extensions/IERC20Metadata.sol)
+
+pragma solidity ^0.8.15;
+
+import {IERC20} from "./IERC20.sol";
+
+/**
+ * @dev Interface for the optional metadata functions from the ERC-20 standard.
+ */
+interface IERC20Metadata is IERC20 {
+    /**
+     * @dev Returns the name of the token.
+     */
+    function name() external view returns (string memory);
+
+    /**
+     * @dev Returns the symbol of the token.
+     */
+    function symbol() external view returns (string memory);
+
+    /**
+     * @dev Returns the decimals places of the token.
+     */
+    function decimals() external view returns (uint8);
+}

contracts/IERC4626.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.1.0) (interfaces/IERC4626.sol)
+
+pragma solidity ^0.8.15;
+
+import {IERC20} from "./IERC20.sol";
+import {IERC20Metadata} from "./IERC20Metadata.sol";
+
+/**
+ * @dev Interface of the ERC-4626 "Tokenized Vault Standard", as defined in
+ * https://eips.ethereum.org/EIPS/eip-4626[ERC-4626].
+ */
+interface IERC4626 is IERC20, IERC20Metadata {
+    event Deposit(address indexed sender, address indexed owner, uint256 assets, uint256 shares);
+
+    event Withdraw(
+        address indexed sender,
+        address indexed receiver,
+        address indexed owner,
+        uint256 assets,
+        uint256 shares
+    );
+
+    /**
+     * @dev Returns the address of the underlying token used for the Vault for accounting, depositing, and withdrawing.
+     *
+     * - MUST be an ERC-20 token contract.
+     * - MUST NOT revert.
+     */
+    function asset() external view returns (address assetTokenAddress);
+
+    /**
+     * @dev Returns the total amount of the underlying asset that is “managed” by Vault.
+     *
+     * - SHOULD include any compounding that occurs from yield.
+     * - MUST be inclusive of any fees that are charged against assets in the Vault.
+     * - MUST NOT revert.
+     */
+    function totalAssets() external view returns (uint256 totalManagedAssets);
+
+    /**
+     * @dev Returns the amount of shares that the Vault would exchange for the amount of assets provided, in an ideal
+     * scenario where all the conditions are met.
+     *
+     * - MUST NOT be inclusive of any fees that are charged against assets in the Vault.
+     * - MUST NOT show any variations depending on the caller.
+     * - MUST NOT reflect slippage or other on-chain conditions, when performing the actual exchange.
+     * - MUST NOT revert.
+     *
+     * NOTE: This calculation MAY NOT reflect the “per-user” price-per-share, and instead should reflect the
+     * “average-user’s” price-per-share, meaning what the average user should expect to see when exchanging to and
+     * from.
+     */
+    function convertToShares(uint256 assets) external view returns (uint256 shares);
+
+    /**
+     * @dev Returns the amount of assets that the Vault would exchange for the amount of shares provided, in an ideal
+     * scenario where all the conditions are met.
+     *
+     * - MUST NOT be inclusive of any fees that are charged against assets in the Vault.
+     * - MUST NOT show any variations depending on the caller.
+     * - MUST NOT reflect slippage or other on-chain conditions, when performing the actual exchange.
+     * - MUST NOT revert.
+     *
+     * NOTE: This calculation MAY NOT reflect the “per-user” price-per-share, and instead should reflect the
+     * “average-user’s” price-per-share, meaning what the average user should expect to see when exchanging to and
+     * from.
+     */
+    function convertToAssets(uint256 shares) external view returns (uint256 assets);
+
+    /**
+     * @dev Returns the maximum amount of the underlying asset that can be deposited into the Vault for the receiver,
+     * through a deposit call.
+     *
+     * - MUST return a limited value if receiver is subject to some deposit limit.
+     * - MUST return 2 ** 256 - 1 if there is no limit on the maximum amount of assets that may be deposited.
+     * - MUST NOT revert.
+     */
+    function maxDeposit(address receiver) external view returns (uint256 maxAssets);
+
+    /**
+     * @dev Allows an on-chain or off-chain user to simulate the effects of their deposit at the current block, given
+     * current on-chain conditions.
+     *
+     * - MUST return as close to and no more than the exact amount of Vault shares that would be minted in a deposit
+     *   call in the same transaction. I.e. deposit should return the same or more shares as previewDeposit if called
+     *   in the same transaction.
+     * - MUST NOT account for deposit limits like those returned from maxDeposit and should always act as though the
+     *   deposit would be accepted, regardless if the user has enough tokens approved, etc.
+     * - MUST be inclusive of deposit fees. Integrators should be aware of the existence of deposit fees.
+     * - MUST NOT revert.
+     *
+     * NOTE: any unfavorable discrepancy between convertToShares and previewDeposit SHOULD be considered slippage in
+     * share price or some other type of condition, meaning the depositor will lose assets by depositing.
+     */
+    function previewDeposit(uint256 assets) external view returns (uint256 shares);
+
+    /**
+     * @dev Mints shares Vault shares to receiver by depositing exactly amount of underlying tokens.
+     *
+     * - MUST emit the Deposit event.
+     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
+     *   deposit execution, and are accounted for during deposit.
+     * - MUST revert if all of assets cannot be deposited (due to deposit limit being reached, slippage, the user not
+     *   approving enough underlying tokens to the Vault contract, etc).
+     *
+     * NOTE: most implementations will require pre-approval of the Vault with the Vault’s underlying asset token.
+     */
+    function deposit(uint256 assets, address receiver) external returns (uint256 shares);
+
+    /**
+     * @dev Returns the maximum amount of the Vault shares that can be minted for the receiver, through a mint call.
+     * - MUST return a limited value if receiver is subject to some mint limit.
+     * - MUST return 2 ** 256 - 1 if there is no limit on the maximum amount of shares that may be minted.
+     * - MUST NOT revert.
+     */
+    function maxMint(address receiver) external view returns (uint256 maxShares);
+
+    /**
+     * @dev Allows an on-chain or off-chain user to simulate the effects of their mint at the current block, given
+     * current on-chain conditions.
+     *
+     * - MUST return as close to and no fewer than the exact amount of assets that would be deposited in a mint call
+     *   in the same transaction. I.e. mint should return the same or fewer assets as previewMint if called in the
+     *   same transaction.
+     * - MUST NOT account for mint limits like those returned from maxMint and should always act as though the mint
+     *   would be accepted, regardless if the user has enough tokens approved, etc.
+     * - MUST be inclusive of deposit fees. Integrators should be aware of the existence of deposit fees.
+     * - MUST NOT revert.
+     *
+     * NOTE: any unfavorable discrepancy between convertToAssets and previewMint SHOULD be considered slippage in
+     * share price or some other type of condition, meaning the depositor will lose assets by minting.
+     */
+    function previewMint(uint256 shares) external view returns (uint256 assets);
+
+    /**
+     * @dev Mints exactly shares Vault shares to receiver by depositing amount of underlying tokens.
+     *
+     * - MUST emit the Deposit event.
+     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the mint
+     *   execution, and are accounted for during mint.
+     * - MUST revert if all of shares cannot be minted (due to deposit limit being reached, slippage, the user not
+     *   approving enough underlying tokens to the Vault contract, etc).
+     *
+     * NOTE: most implementations will require pre-approval of the Vault with the Vault’s underlying asset token.
+     */
+    function mint(uint256 shares, address receiver) external returns (uint256 assets);
+
+    /**
+     * @dev Returns the maximum amount of the underlying asset that can be withdrawn from the owner balance in the
+     * Vault, through a withdraw call.
+     *
+     * - MUST return a limited value if owner is subject to some withdrawal limit or timelock.
+     * - MUST NOT revert.
+     */
+    function maxWithdraw(address owner) external view returns (uint256 maxAssets);
+
+    /**
+     * @dev Allows an on-chain or off-chain user to simulate the effects of their withdrawal at the current block,
+     * given current on-chain conditions.
+     *
+     * - MUST return as close to and no fewer than the exact amount of Vault shares that would be burned in a withdraw
+     *   call in the same transaction. I.e. withdraw should return the same or fewer shares as previewWithdraw if
+     *   called
+     *   in the same transaction.
+     * - MUST NOT account for withdrawal limits like those returned from maxWithdraw and should always act as though
+     *   the withdrawal would be accepted, regardless if the user has enough shares, etc.
+     * - MUST be inclusive of withdrawal fees. Integrators should be aware of the existence of withdrawal fees.
+     * - MUST NOT revert.
+     *
+     * NOTE: any unfavorable discrepancy between convertToShares and previewWithdraw SHOULD be considered slippage in
+     * share price or some other type of condition, meaning the depositor will lose assets by depositing.
+     */
+    function previewWithdraw(uint256 assets) external view returns (uint256 shares);
+
+    /**
+     * @dev Burns shares from owner and sends exactly assets of underlying tokens to receiver.
+     *
+     * - MUST emit the Withdraw event.
+     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
+     *   withdraw execution, and are accounted for during withdraw.
+     * - MUST revert if all of assets cannot be withdrawn (due to withdrawal limit being reached, slippage, the owner
+     *   not having enough shares, etc).
+     *
+     * Note that some implementations will require pre-requesting to the Vault before a withdrawal may be performed.
+     * Those methods should be performed separately.
+     */
+    function withdraw(uint256 assets, address receiver, address owner) external returns (uint256 shares);
+
+    /**
+     * @dev Returns the maximum amount of Vault shares that can be redeemed from the owner balance in the Vault,
+     * through a redeem call.
+     *
+     * - MUST return a limited value if owner is subject to some withdrawal limit or timelock.
+     * - MUST return balanceOf(owner) if owner is not subject to any withdrawal limit or timelock.
+     * - MUST NOT revert.
+     */
+    function maxRedeem(address owner) external view returns (uint256 maxShares);
+
+    /**
+     * @dev Allows an on-chain or off-chain user to simulate the effects of their redeemption at the current block,
+     * given current on-chain conditions.
+     *
+     * - MUST return as close to and no more than the exact amount of assets that would be withdrawn in a redeem call
+     *   in the same transaction. I.e. redeem should return the same or more assets as previewRedeem if called in the
+     *   same transaction.
+     * - MUST NOT account for redemption limits like those returned from maxRedeem and should always act as though the
+     *   redemption would be accepted, regardless if the user has enough shares, etc.
+     * - MUST be inclusive of withdrawal fees. Integrators should be aware of the existence of withdrawal fees.
+     * - MUST NOT revert.
+     *
+     * NOTE: any unfavorable discrepancy between convertToAssets and previewRedeem SHOULD be considered slippage in
+     * share price or some other type of condition, meaning the depositor will lose assets by redeeming.
+     */
+    function previewRedeem(uint256 shares) external view returns (uint256 assets);
+
+    /**
+     * @dev Burns exactly shares from owner and sends assets of underlying tokens to receiver.
+     *
+     * - MUST emit the Withdraw event.
+     * - MAY support an additional flow in which the underlying tokens are owned by the Vault contract before the
+     *   redeem execution, and are accounted for during redeem.
+     * - MUST revert if all of shares cannot be redeemed (due to withdrawal limit being reached, slippage, the owner
+     *   not having enough shares, etc).
+     *
+     * NOTE: some implementations will require pre-requesting to the Vault before a withdrawal may be performed.
+     * Those methods should be performed separately.
+     */
+    function redeem(uint256 shares, address receiver, address owner) external returns (uint256 assets);
+}